Streptonigrin is a potent, although toxic, anticancer agent produced by Streptomyces flocculus. The work proposed herein will: (1) Utilize our previous identification of beta-methyltryptophan as an intermediate in streptonigrin biosynthesis as the focus for preparing streptonigrin analogs by mutasynthesis. Our approach will be to prepare a mutant blocked in the pathway between tryptophan and beta-methyltryptophan, synthesize radiolabeled beta-methyltryptophan analogs and feed them to our mutant(s) and isolate and test the resulting metabolites for potential anticancer activity. (2) Continue our studies of streptonigrin biosynthesis, focusing mainly on the origin of the quinoline portion of the molecule. This will provide additional insights to the scope of the chemistry of biological systems, and may provide additional opportunities for mutasynthetic approaches to streptonigrin analogs. This work may provide useful new anticancer agents, should yield information on the substrate specificity of enzymes in secondary metabolism, and will make available a variety of radiolabeled tryptophan analogs that could be used in a variety of studies besides the work proposed in this application.